This invention relates generally to hermetic refrigeration compressors, and more particularly to suction or inlet mufflers for refrigeration compressors of the type used in household appliances.
Refrigeration compressors are used in a large number of household appliances, such as refrigerators, freezers, dehumidifiers, and room air conditioners, and in these applications it is most important that the noise generated by operation of the compressor be held to a minimum practical level. Most of these compressors use a reciprocating piston operating at a relatively high speed, such as 3500 r.p.m., and this produces a relatively high frequency series of pulses for both the suction or inlet portion of the piston stroke and the discharge or outlet portion of the piston stroke. Because these pulsations naturally produce noise at audible frequencies, it has long been necessary to provide separate muffler arrangements at both the inlet and outlet of the compressor cylinder to dampen these pulsations and minimize the noise produced thereby. While such inlet and outlet mufflers are often made with a similar construction, it is recognized that the outlet or discharge muffler must necessarily be able to handle substantially higher internal pressures than the inlet muffler, and that the inlet muffler may therefore be made of a different or lower-cost construction to accomplish the same results.
Another matter that has become increasingly important in recent years is that the compressor be as efficient as possible with regard to the amount of cooling produced with respect to the amount of electrical energy input to the electric motor driving the compressor. It has been found that there are many ways in which compressor efficiency can be increased, including increasing the efficiency of the electrical motor driving the compressor, as well as decreasing the mechanical friction between the various moving parts. Other means for increasing overall efficiency include eliminating restrictions in the flow of the refrigerant gas through the compressor, as well as increasing the thermal efficiency. In many prior designs, the return refrigerant gas from the system evaporator was caused to circulate throughout the interior of the compressor shell to provide a cooling effect before the gas was fed into the inlet of the suction muffler. However, this cooling effect causes the refrigerant in the suction muffler to be heated, which reduces the thermal efficiency of the compressor.